This invention relates to a method and apparatus for testing electrically controlled electric motors and particularly to such an apparatus for onsite testing of such motors.
With the development of electronic controls, many electric motors are presently constructed with integrated on-site electronic controls for controlling the operation and operational state of an electric motor. A typical example developed by the assignee of this invention is a motor-pump unit forming a part of jetted water system such as present in a spa, whirlpool tub and the like. The motor is desirably controlled through a pneumatic actuator located at the tub for purposes of optimizing safety from electrical hazards by the operator. Various electronic timers, water pressure and level controls may be incorporated into the more sophisticated jetted tub devices. A particularly satisfactory control system incorporating an electronic control is disclosed in the co-pending application of James L. King, entitled "Electric Motors Having Integrated Control Housing And Method Of Fabrication" which was filed on Feb. 6, 1989 with Ser. No., 07/306,887. As more fully disclosed in the above application, the motor is constructed with a separate control chamber within which various control components including an electronic control can be mounted and wherein a power supply cable is connected to the motor through a separate interconnecting jumper cable to permit the direct energization of the motor in the event there is a system failure. This permits onsite determination of whether the motor has or has not failed, and by interference whether a failure arose within the electronic control. If the electronic control failure is implied by motor operation, the control can be removed and returned to a service station, thereby avoiding the necessity of removing the motor-pump unit. There is a distinct advantage both from a standpoint of cost and convenience to the customer provided by the above system. However, such system requires a special cable connection which is well justified in view of the alternate prior art mode of operation. However, the system does not permit separate on-site testing of the control, short conditions and the like. The electronic control is often provided with various protective systems but still constitutes a particular source of possible system failure and/or malfunction. There is a remaining need for a test system which can be applied to a conventionally connected electric motor with an electronic control to separately detect a fault location in the motor or the control.
In a conventionally connected electric motor, a circuit terminal board is provided within the motor. The terminal board includes an appropriate power terminal connected to the incoming power lines for parallel connection to the motor and the control in combination with at least one additional terminal for selective interconnection of control output of the electronic control into circuit with the power supply connection and the motor. Thus for example, in a typical jetted pump supply, a power terminal circuit board is provided including first and second power terminals for direct connection to the incoming power supply, with one terminal connected to the motor and timer. Additional terminals interconnect the power supply to an electronic timer having an output switch connected at the terminal board to the motor to establish a time controlled energization of the motor.
A non-operative or malfunctioning electronically controlled motor will generally be related to one of the six following basic faults: (1) motor failure, (2) electronic control failure, (3) motor and control failure, (4) power supply failure, (5) motor with a short-to-ground and operating under a hazardous condition, and (6) controller shorted-to-ground operating under a hazardous condition. Thus, even if the motor should check out as not operating properly, there is no assurance that the control, in fact, is the source of the fault. When the operator or service personnel is called to service the motor, the motor is disconnected from the power supply. The timer and motor connection to the power supply is also opened. If the motor operates, the fault is within the timer control. The timer control is removed and returned for servicing at the service shop, as previously noted.
Various fault conditions may however exist and it would be well if the service personnel could provide a direct on-site monitor and check of the input and output state of the electronic control such as an electric timer having output contacts controlling the energization of the motor.
There is therefore a need for a simple, effective and low-cost testing apparatus for on-site testing of both the motor and the separate control to determine precisely if either or both units are malfunctioning.